The present invention relates to coin detectors and, more particularly, to electronic coin acceptors which act to discriminate between genuine and non-authentic coins for a predetermined denomination based upon measurable characteristics of the coins tested.
Vending and gaming machines accepting coins in return for products or services are commonplace today. In such machines, each coin inserted is typically inspected and evaluated for authenticity in a predetermined manner. Thereafter, the coin is accepted or rejected based upon the results of such evaluation and credit and products and/or services are provided to the consumer in an amount corresponding to the value of the coins accepted.
Coin evaluation has heretofore typically been accomplished by various mechanical and/or electronic devices employing a myriad of inspection or measurement techniques. In recent years electronic testors have been found to be preferable over merely mechanical devices and are now the more common in industry use. One preferred form of electronic coin detection apparatus is disclosed in U.S. Pat. No. 4,354,587, as issued to Ronald C. Davis on Oct. 19, 1982 and assigned to Third Wave Electronics Co., the assignee of the instant invention. The device disclosed in U.S. Pat. No. 4,354,587 operates on the principle that a metallic coin, passing through a magnetic field of an RF oscillator coil, will create eddy current losses. The magnitude of this loss is dependent upon the mass and conductivity of the coin under test. Circuitry is provided to measure the amount of the eddy current loss, and if the loss falls within certain narrow limits, the coin is determined to be valid. Upon detection of a valid coin, appropriate coin acceptance may be performed with the value of the accepted coin being credited to the consumer. A coin exhibiting losses outside predefined limits is considered to be invalid and is rejected. The device is highly advantageous in single denomination applications since it is fast and accurate in operation and its simplified electronic structure is compact, not subject to wear and relatively inexpensive.
The accuracy of the coin acceptor apparatus disclosed in U.S. Pat. No. 4,354,587 has been determined to be somewhat dependent upon the value of the coin for which a particular acceptor is designed. For example, very few slugs or foreign coins can successfully mimic the characteristics of the U.S. quarter. Hence, for U.S. quarters the accuracy of the aforesaid coin acceptor is considered excellent. However, it appears that the Eisenhower silver dollar is susceptible to slugging since it can be mimicked by certain washers or slugs consisting of a lead/zinc mixture having similar mass and conductivity characteristics. Since these content characteristics are employed by the coin acceptor apparatus disclosed in U.S. Pat. No. 4,354,587 as a basis for its discrimination decisions, it has been found that coin acceptors designed for Eisenhower silver dollars can sometimes be defeated by slugs of this type.
It has been found that the accuracy of coin acceptor apparatus employing the electrical, magnetic or mechanical characteristics of a coin for purposes of determining genuineness may be markedly increased by additionally testing the reflection characteristics exhibited thereby. This occurs since the very materials employed to provide a slug with appropriate electrical, magnetic or mechanical characteristics will generally impart an overall cast to the slug which causes marked differences in reflectivity between a valid coin and a slug having such appropriate electrical, magnetic or mechanical characteristics. Furthermore, those marked differences in reflectivity may be advantageously relied upon to enhance the accuracy manifested by coin detectors, and under certain circumstances, be employed to configure a coin acceptor per se.
It is therefore an object of the present invention to provide improved coin detector apparatus.
It is an additional object of the present invention to provide coin detector apparatus which tests for coin validity based upon the surface reflectivity of a coin under test.
It is still a further object of the present invention to provide coin detector apparatus providing a two-tier test for validity of a coin, including a first test for content and a second test for reflectivity of the coin under test.